Pyrolysis machine

ABSTRACT

Useful byproducts are recovered through the pyrolytic processing of biomass material such as vegetation, paper, or worn tires. The process is conducted in a sealed enclosure under vacuum or other controlled atmosphere. The biomass material is ablated and burned by crunching between counter-rotating rollers whose inner walls have been exposed to a highly heated fluid. The biomass material is preheated by injecting into the feeding duct super-heated dry steam. A condenser within the enclosure reduces resulting vapors into oils that can be drained from the enclosure pan. Solid combustion residue is abstracted from the enclosure by an Archimedes screw.

This application is a 371 of PCT/US05/2934, filed Aug. 18, 2005, whichis a Continuation-In-Part of Ser. No. 10/921,033, filed Aug. 18, 2004,now U.S. Pat. No. 7,108,767.

FIELD OF THE INVENTION

This invention relates to pyrolysis, and more particularly to method forpyrolytically processing waste biomass material into useful byproducts.

BACKGROUND

The use of pyrolysis as a means of recovering oil and carbon byproductsby combustion of waste material under vacuum is well-known. Anapplication of this process is described in “The Vacuum Pyrolysis ofUsed Tires and Uses for Oil and Carbon Black Products by C. Roy, A.Chaala, and H. Darmstadt—Elsevier Journal of Analytical and AppliedPyrolysis Vol. 51 (1999) p. 201-221” which paper is incorporated intothis specification by this reference.

The conventional pyrolytic process involves shedding biomass materialinto small chips or debris that are then pyrolyzed under a controlledatmosphere. A common method consists of spreading the debris over aconveyer belt that passes through a high temperature furnace. Debris mayalso be incinerated by mixing them with super-heated sand. The pyrolyzedmaterial is then treated chemically or mechanically to extract desiredbi-products. The prior art methods require multi-step treatment,including pre-shredding of large articles, through complex equipment ata relatively slow throughput rate.

This invention results from an attempt to devise a simple and moreefficient method and apparatus to recover large quantities of usefulbyproducts from the pyrolysis of a large variety of biomass wastematerial.

SUMMARY

The embodiments of this invention provide a relatively simple apparatusinto which the various processes of ablative pyrolysis can beaccomplished in a single and continuous operation which is easilycontrolled and self-regulating, at a great economy of energy.

These embodiments include feeding biomass material in an enclosure undervacuum or other controlled atmosphere between counter-rotating rollersthat are closely spaced-apart and whose circumferential outer surfaceshave been heated by exposure to a hot fluid. The fluid is injected intothe interior of the cylinder through an axial duct and extractedtherefrom through another duct coaxial with the first one, and directedagainst the inside surface of each of the cylinder walls by a stationarycylindrical body having an axial intake port and a plurality ofperipheral outlets that direct the blast of highly heated fluid, forexample, super-heated steam, against the wall of the roller. The biomassmaterial is fed between the rollers through a chute into whichsuper-heated dry steam is injected in order to preheat the material. Acondenser in the enclosure turns vaporized oils into liquids that can bedrained from the pan of the apparatus. Solid carbon residue areextracted by means of an Archimedes screw at the bottom of the pan.

In some embodiments there is provided an apparatus for pyrolyticprocessing of biomass material into useful byproducts, which comprises:an enclosure; a pair of axially parallel, rotating rollers in saidenclosure, said rollers being narrowly spaced-apart to grab and crunchsaid biomass material fed therebetween; means for rotating said rollers;means for heating said rollers to an incinerating temperature; means forfeeding said biomass material between said rollers; and means forextracting said byproducts from said enclosure.

In other embodiments, the means for heating comprise means forcirculating a continuous flow of highly heated fluid within saidrollers. In some embodiments the means for circulating comprise: each ofsaid rollers having a circumferential wall made of heat-conductingmaterial, and having inner and outer circumferential surfaces; a bodycoaxially mounted within said roller in close proximity to saidcircumferential wall, said body having a plurality of peripheral outletsand at least one intake port; and means for passing said highly-heatedfluid through said intake port and out said outlets against said innercircumferential surface. In some embodiments the means for passingcomprise: first conduit means for injecting said highly heated fluidinto said body through an axial aperture in said roller; and secondconduit means for drawing said highly heated fluid out of said roller.In some embodiments the means for passing further comprise said secondconduit means being formed through a second axial aperture in saidroller. In some embodiments the means for passing further comprise saidsecond conduit means coaxially surrounding said first conduit meansthrough said aperture.

In yet other embodiments the means for extracting comprise: means forcondensing hot combustion gases into liquids; and means for drawing saidliquids out of the enclosure. In some embodiments the liquids comprise afuel combustible by said means for heating. In some embodiments themeans for extracting further comprise means for extracting combustionresidue from said enclosure. In some embodiments the means forextracting comprise an Archimedes screw.

In yet other embodiments the said means for feeding comprise: a chutehaving an exit above the space between said rollers; and means forfeeding dry heated steam into said chute; whereby the biomass materialis preheated by said steam into said chute before dropping between therollers. In some embodiments the means for rotating comprise means forturning said rollers in opposite directions from each other, and atslightly different speeds. In some embodiments the enclosure ishermetically sealed; whereby said processing can be performed undercontrolled atmosphere.

In yet other embodiments the apparatus further comprises: anhermetically sealable chamber adjacent to said enclosure; a closablepassageway between said enclosure and chamber; and means for adjustingthe atmosphere in said chamber to that of said enclosure; wherebybiomass material can be placed into said chamber, the chamber sealed,and its atmosphere adjusted before opening said passageway and admittingsaid biomass material into said enclosure.

Other embodiments provide a pyrolytic method for converting biomassmaterial into useful byproducts, which comprises ablating and pyrolyzingsaid biomass material between highly heated, counter-rotating crunchingrollers. Some embodiments further comprise heating the circumferentialsurfaces of said rollers with a highly heated fluid. In some embodimentssaid step of heating comprises injecting said highly heated fluid intosaid rollers. Some embodiments further comprise turning said rollers atslightly different speeds. Some embodiments further comprise turningsaid rollers in an opposite rotational direction, whereby an obstructionis cleared. Some embodiments further comprise conducting said ablatingin a sealed enclosure under a controlled atmosphere. Some embodimentsfurther comprise conducting said ablating under vacuum. Some embodimentsfurther comprise condensing vaporized fluids present in said enclosure.Some embodiments further comprise: feeding said biomass material to saidrollers through a chute; and injecting hot dry steam into said chute topreheat said biomass material. Some embodiments further compriseimparting turbulences into said highly heated fluid. In some embodimentssaid rollers are heated by heat-transfer from a highly heated fluid. Insome embodiments said atmosphere is formulated and adjusted to achieve aspecific chemical reaction during said processing. In some embodimentssaid highly heated fluid is taken from a group consisting essentially ofsuper-heated steam, highly heated molten salts, highly heated oils,combustion gasses, plasma and open flame.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagrammatic, cross-sectional view of the pyrolysis machineaccording to the invention;

FIG. 2 is a fragmentary, perspective view of a roller-heating mechanism;and

FIG. 3 is a perspective view of a pyrolysis machine adapted to theprocessing of reclaimed tires.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawing, there is shown in the diagram of FIG. 1,an apparatus 1 particularly adapted to the practice the ablativepyrolytic process of converting biomass material such as paper, woodchips or other vegetation debris in order to extract from them usefulbyproducts such as oils or other liquids, and carbon particles and othersolids. The biomass material 2 is fed to a pair of counter-rotatingcrunching rollers 3, 4 held in a sealed enclosure 5. The biomassmaterial is dropped into the enclosure through a chute 6. The rollersare axially parallel and their circumferential outer surfaces 7, 8 arenarrowly spaced-apart to grab, crunch and burn the pieces of biomassmaterial. The walls of the rollers are made of a heat-transmittingmaterial, preferably stainless steel and are heated from the inside. Inother words, each of the outer surfaces is heated from a heat sourcelocated radially inwardly from the outer surface, thus making bothrollers separately internally heated. The rollers can include electricheating elements, but are preferably exposed to a flow of highly heatedfluid such as a super-heated gas.

As more specifically illustrated in FIG. 2, a cylindrical body 9 iscoaxially housed into each roller 3, 4. The cylindrical body does notrotate, but forms a chamber 10 having an axial intake port 11 connectedto a duct 12 passing through an axial aperture 13 in one of the endwalls 14 of the roller.

The chamber has also a plurality of peripheral outlets or pores 15 whichblast a pressurized highly heated fluid admitted through the intake 11against the inner surface 16 of the roller's circumferential wall. Ithas been found that this form of impingement heat transfer is highlyeffective. The highly heated fluid is evacuated from the space 17between the cylindrical body 9 and the roller wall inner surface 16 byway of an exit conduit 18 coaxially surrounding the intake duct 12. Theend wall 14 of the roller is rotatively supported by a water-cooledroller bearing 19 fitted around the exit conduit 18. The opposite endwall 20 of the roller is welded to an axial shaft 21 supported by anouter structure (not shown in the drawing) by another roller bearing 22.The shaft mounts a sprocket wheel 23 engaging a chain that drives theroller. Alternately or additionally, another exit conduit 24 can beformed through the axial shaft 21 in communication with a second axialaperture formed through the opposite end wall 20 of the roller.

The highly heated fluid is preferably super-heated steam or highlyheated oil or molten salt which is heated to a temperature calculated toincinerate the biomass material over a range of approximately 400degrees to 1,000 degrees Celsius in a boiler (not shown in the drawing).Turbulences are preferably imparted in the highly heated fluid in orderto maximize the heat transfer to the roller. Alternatively, the highlyheated fluid can be combustion gasses including an open flame or otherplasma generated by electrically ionized gas for example. The combustiongasses can be channeled from an ignition source or can be a fuel ignitedin the presence of an oxidizing gas such as air within the rollers. Thefuel can by conveniently derived from combustible byproducts of thepyrolytic process itself. Super-heated steam is used as the highlyheated fluid in this preferred embodiment.

As shown in the diagram of FIG. 1, the outer peripheries of the rollersare surrounded by hemispherical heat shields 25, 26 supported bybrackets 27, 28 welded at their bases to the floor of the enclosure 5.Sets of condenser coils 29, 30 into which a cooling fluid is circulated,are positioned between the heat shields and the side walls 31 of theenclosure. The coils cause vaporized fluids such as oil which emanatesfrom the burning biomass material to condense into a liquid which iscontinuously drained from the bottom pan 32 of the enclosure throughappropriate ports 33 and conduits.

Pulverized or solid residue from the combustion of the biomass materialfall into a trough 34 from which they are extracted by a Archimedesscrew 35.

As indicated by the arrows 36 flow of dry, super-heated steam 37 isinjected into the chute 2 through radial apertures 38 in order topreheat the biomass material. The material is preferably packed and fedloosely to the device in order to allow easy and efficient circulationof the heating steam therethrough. The steam is allowed to escape up thechute. It should be understood that the super-heated, dry steam can bethe same fluid that is used for heating the rollers and is fed to thechute from the exit ports 18 of the rollers.

The enclosure 5 may be subject to a vacuum or to any other type ofcontrolled and regulated atmosphere in order to accommodate a variety ofbiomass material. The atmosphere may be formulated and adjusted totrigger a specific chemical reaction during the pyrolysis process.

As illustrated in the diagram of FIG. 3, whole, bulky articles such asthe illustrated worn tire 40 may be processed by an adaptation of theabove-described apparatus. In this case, the chute is replaced by a box41 connected through a closable passageway 42 to a conditioning chamber43 large enough to accommodate at least one tire. With the passagewayhermetically closed by a sliding gate 44 the tire is introduced into thebox through a feeding opening 45. A door 46 closing the opening ishermetically sealed, and the atmosphere within the box is brought to thesame control conditions as the enclosure of the apparatus. When thechamber and the enclosure are in equilibrium, the sliding gate 44 iswithdrawn and the tire allowed to roll under gravity and drop toward therollers. It should be noted that no pre-shredding of the tire isrequired.

In order to facilitate the ablation of the tire or other biomassmaterial, the outer peripheral surfaces 7, 8 of the rollers are providedwith indentations 47 which are interspaced from one roller to the other.More friction and shredding action is obtained by running the rollers atslightly different speeds from one another. At least one of the rollersmay be supported by a resilient structure that allows for slight andmomentary separation of the rollers when they grab a non-frangiblepieces of material.

The rotation of each roller is independent from the other so that notonly the speed, but also the direction of rotation may be separatelyaltered to maximize ablation or to clear obstructing matter.

For best results, wood chips and other vegetable material should have awater content not exceeding approximately 15% per weight. When theheated gas is brought from the rollers into the chute it is still in asuper-heated condition but to a lesser degree than when fed to theheating bodies of the rollers. When fed at the base of the chute closeto the rollers, the heated gas helps dry and pre-condition the incomingchips, and, at the same time generates a large plume of low temperaturesteam that drives out any air that is being carried in with the chips.Addition of a small amount of nitrogen gas helps remove any enteringoxygen. The dried wood chips now devoid of contaminating oxygen drop outof the chute and accumulate against the rotating rollers at a feedingrate that can be set as a function of the temperature, speed of rotationand the rate of ablation of the wood stock being processed. This feedingmethod is by design self-regulating, where no special regulating controlis needed.

The ratio of recovered bio-oils and gases, such as methane, carbonmonoxide and hydrogen can be modified by adjusting the atmosphericpressure within the chamber, the temperature of the rollers and thedegree of preheating. Lower temperatures tend to favor the extraction oforganic acids such as formic and acidic acids or alcohols. An halogenatmosphere can yield halogenated bio-oils. Non-condensing gases thataccumulate within the enclosure can be collected and exploited as asource or heat or pressure or used in some combustion device to produceenergy. The powder or solid residue which is collected at the bottom ofthe enclosure will include activated carbon. This product is alsodependent upon the biomass material condition and the reactiontemperature being used and may not need further processing. The carbonresidue can also be heated with sulfuric acid to produce carbondisulfide and hydrogen.

It should also be noted that the use of burning rollers avoids the needof pre-shredding tires and other such items prior to feeding into thepyrolysis apparatus. Sifting equipment can be used to separate metalliccomponents such as tire belts from carbon residue according to methodswell-known to the mechanical arts.

While the preferred embodiments of the invention have been disclosed,modifications can be made and other embodiments may be devised withoutdeparting from the spirit of the invention and the scope of the appendedclaims.

1. An apparatus, for pyrolytic processing of biomass material intouseful byproducts, which comprises: an enclosure; a pair ofcounter-rotating rollers in said enclosure, said rollers being narrowlyspaced-apart to grab and crunch said biomass material fed therebetween;wherein each of said rollers comprises: a circumferential wall made ofheat-conducting material, and having an outer circumferential surface;and, a source of non-combusting incinerating temperature heat locatedradially inwardly from said outer circumferential surface.
 2. Theapparatus of claim 1, wherein said source of heat comprises a continuousflow of highly heated fluid within said rollers.
 3. The apparatus ofclaim 2, wherein said apparatus further comprises: each of said rollershaving an inner circumferential surface; a body coaxially mounted withineach of said rollers in close proximity to said circumferential wall,said body having a plurality of peripheral outlets and at least oneintake port; and an amount of highly-heated fluid passing through saidintake port and out said outlets against said inner circumferentialsurface.
 4. The apparatus of claim 3, which further comprises: a firstconduit injecting said highly heated fluid into said body through anaxial aperture in said roller; and a second conduit drawing said highlyheated fluid out of said roller.
 5. The apparatus of claim 4, whereinsaid second conduit is formed through a second axial aperture in saidroller.
 6. The apparatus of claim 4, wherein said second conduit iscoaxially surrounding said first conduit through said aperture.
 7. Theapparatus of claim 1, which further comprises: said apparatus creatingan amount of hot combustion gases; a condenser condensing said amount ofhot combustion gases into liquids; and, a drainage port draining saidliquids out of the enclosure.
 8. The apparatus of claim 7, wherein saidliquids comprise a fuel combustible by said apparatus.
 9. The apparatusof claim 1, which further comprises a trough for extracting combustionresidue from said enclosure.
 10. The apparatus of claim 9, which furthercomprises an Archimedes screw located in said trough.
 11. The apparatusof claim 1, wherein said apparatus further comprises: a chute having anexit above the space between said rollers; and an amount of dry heatedsteam injected into said chute; whereby the biomass material ispreheated by said steam into said chute before dropping between therollers.
 12. The apparatus of claim 1, wherein said rollers turn atslightly different speeds.
 13. The apparatus of claim 1, wherein saidenclosure is hermetically sealed; whereby said processing can beperformed under controlled atmosphere.
 14. The apparatus of claim 13,which further comprises: an hermetically sealable chamber adjacent tosaid enclosure; a closable passageway between said enclosure andchamber; and means for adjusting the atmosphere in said chamber to thatof said enclosure; whereby biomass material can be placed into saidchamber, the chamber sealed, and its atmosphere adjusted before openingsaid passageway and admitting said biomass material into said enclosure.15. A pyrolytic method for converting biomass material into usefulbyproducts, which comprises ablating and pyrolizing said biomassmaterial between highly heated, internally heated by a source ofnon-combusting incinerating temperature heat, counter-rotating crunchingrollers.
 16. The method of claim 15, which further comprise heating thecircumferential surfaces of said rollers with a highly heated fluid. 17.The method of claim 16, wherein said step of heating comprises injectingsaid highly heated fluid into said rollers.
 18. The method of claim 15,which further comprises turning said rollers at slightly differentspeeds.
 19. The method of claim 15, which further comprises turning saidrollers in an opposite rotational direction, whereby an obstruction iscleared.
 20. The method of claim 15, which further comprises conductingsaid ablating in a sealed enclosure under a controlled atmosphere. 21.The method of claim 20, which further comprises conducting said ablatingunder vacuum.
 22. The method of claim 20, which further comprisescondensing vaporized fluids present in said enclosure.
 23. The method ofclaim 15, which further comprises: feeding said biomass material to saidrollers through a chute; and injecting hot dry steam into said chute topreheat said biomass material.
 24. The method of claim 17, which furthercomprises imparting turbulences into said highly heated fluid.
 25. Themethod of claim 15, wherein said rollers are heated by heat-transferfrom a highly heated fluid.
 26. The method of claim 20, wherein saidatmosphere is formulated and adjusted to achieve a specific chemicalreaction during said processing.
 27. The method of claim 25, whereinsaid highly heated fluid is taken from a group consisting essentially ofsuper-heated steam, highly heated molten salts, highly heated oils,combustion gasses, plasma and open flame.